326 ANATOMICAL TECHNOLOGY. 



the figures, before undertaking the dissection and detailed examina- 

 tion 01 the organ. Later, however, he should again consult it for 

 the descriptive portions. 



§ 851. Aorta (a2.), Ao. (Fig. 91, 92, 93, 94, 95, 96, 99, 100, 101, 102, 

 103, 107, 108). — The large artery springing from the base of the left 

 ventricle and giving off branches to all parts of the body. Its cen- 

 tral portion (as shown in Fig. 91, 101, 102, 108) is strongly arched, 

 and is thence named arcus aorticus. It then passes through the 

 thorax into the abdomen, and the diaphragm therefore indicates 

 the point of demarcation between the aorta thoracica and the aorta 

 abdominalis. This vessel is sometimes, as by StoweU {1), called 

 A. (Arteria) aorta, but the single word seems to be sufficient. 



§ 852. Apex (ventriculi). — The smaller or caudal end of either 

 ventricle, and of either the cavity or the fleshy wall thereof (Fig. 91, 

 92, 93, 98). 



§ 853. Appendix (auriculae) — The ventral extension of either auri- 

 cle (Fig. 91, 95, 96). — The other and larger division of the auricle is the 

 sinus. The limits of the two divisions are not clearly defined, but 

 as a whole the ental surface of the appendix presents more corruga- 

 tions. Sometimes the appendix is called auricle, and the entire 

 cavity is then known as atrium. 



§ 854. Arcus aorticus {az.), arc. ao. — The arch of the aorta 

 (Fig. 92, 101, 102, 108).— See aorta (§ 851) and the explanation of 

 Fig. 101, 102. 



§ 855. Arteria brachio-cephalica {az.), A. hrcph. — The brachio- 

 cephalic artery (Fig. 91, 92, 101, 102, 103, 107, 108).— See explana- 

 tion of Fig. 102. 



§ 856. Arteria cardiaca, A. crd. — A cardiac or coronary artery 

 (Fig. 91, 92, 93, 94, 102). — There are two cardiac arteries, arising 

 from the aortic sinuses of Valsalva and distributed to the substance 

 of the heart. As seen ia Fig. 102, they arise respectively from the 

 right and left sinuses, and are distributed to the corresponding re- 

 gions. The mouth of the right one is shown in Fig. 94. It is wo^ cow- 

 er e*^ by the valve when the latter is opened ; see W. T. Sedgwick (J). 



§ 857. Arteria pulmonalis {az.\ A. plm. — The pulmonary ar- 

 tery (Fig. 91, 92, 93, 95, 99, 100).— This springs from the conus 

 arteriosus at the base of the right ventricle, passes sinistro-cephalad 

 and ventrad of the aorta, and divides into two {A. plm. dxt. and A. 

 plm. sin.), which carry blood to the right and left lung respectively. 



